A Swedish MK1 diesel fuel and a European gasoline of ∼95 RON have been compared in a single cylinder CI engine operating at 1200 RPM with an intake pressure of 2 bar abs., intake temperature of 40° ...

Partially pre-mixed auto-ignition of gasoline to attain low smoke and low NOx at high load in a compression ignition engine and comparison with a diesel fuel

Sensitivity of combustion noise and NOx and soot emissions to pilot injection in PCCI Diesel engines

Effects of port fuel injection (PFI) of n-butanol and EGR on combustion and emissions of a direct injection diesel engine

The optimization procedure adopted in the present investigation is based on Genetic Algorithms (GA) and allows different fitness functions to be simultaneously maximized. The parameters to be optimized are related to the geometric features of the combustion chamber, which ranges of variation are very wide. For all the investigated configurations, bowl volume and squish-to-bowl volume ratio were kept constant so that the compression ratio was the same for all investigated chambers. This condition assures that changes in the emissions were caused by geometric variations only. The spray injection angle was also considered as a variable parameter. The optimization was simultaneously performed for different engine operating conditions, i.e. load and speed, and the corresponding fitness values were weighted according to their occurrence in the European Driving Test. The evaluation phase of the genetic algorithm was performed by simulating the behavior of each chamber with a modified version of the KIVA3V code. The parameters for the sprays and the combustion models were adjusted according to the experimental data of a commercial chamber geometry taken as baseline case. Three fitness functions were defined according to engine emission levels (soot, NOx and HC) and a penalty function was used to account for engine performance. The goal of the optimization process was to select a chamber giving the best compromise of the selected fitness functions. Furthermore, chambers optimizing each single fitness function were also analyzed. The influence of the geometric characteristics on emissions has also been investigated in the paper.

/pdf/optimization-of-the-combustion-chamber-of-direct-injection-10x6iosbas.pdf

Optimization of the Combustion Chamber of Direct Injection Diesel Engines

Analysis of the relation between injection parameter variation and block vibration of an internal combustion diesel engine

The aim of the present work is to evaluate the influence of the pilot injection on combustion of a TDI Diesel engine for different engine torque and speed conditions. For this investigation, pilot injection timing and duration were varied on a wide range of values, and their effects on combustion pressure, rate of heat release, pilot and main combustion delay, combustion process and exhaust emissions in terms of NO x and smoke were analyzed. An in-line, four-cylinder, turbocharged FIAT 1930 cm 3 TDI Diesel engine, equipped with Common Rail injection system, was tested. A piezoelectric sensor was located in the combustion chamber in order to acquire combustion pressure; from these signals, gross heat release rate was,derived in order to analyze the combustion behavior. Pollutant emission levels have been measured by means of a gas analyzer, while for smoke an opacimeter was used. It was found that both timing and duration of pilot injection strongly influence its autoignition tendency; in particular, pilot injection autoignition mainly occurs with low values of timing and high durations. Moreover, pilot injection timing effect is more evident on pilot ignition delay than pilot duration, whereas the effect of both variables on the main ignition delay depends on the engine operating conditions. The effect of pilot injection parameters is evident on engine emission behavior too; in particular, NO x emissions levels are mainly influenced by the pilot duration, whereas pilot timing effect is more evident at lower engine load and speed. Smoke emission seems to be influenced by both variables, but their effect is stronger especially at medium and high load.

Effects of Pilot Injection Parameters on Combustion for Common Rail Diesel Engines

Different injection strategies applied to a common rail direct injection diesel engine were tested for different engine torque and speed conditions. The injection strategies differ for the use of early and pilot injections; during the tests the injection parameters were varied, in terms of duration and timing of early, pilot, and main injections. The combustion behaviour and the engine performances, in terms of brake specific fuel consumption, were analysed. In addition, data on nitrogen oxides (NOx), total unburned hydrocarbons, and particulate emissions were collected.The injection strategy based on both early and pilot injections has been compared with the techniques using either pilot or early injections. Results show that, particularly at lower values of engine torque and speed, the small fuel quantity injected during early injection, coupled with the pilot injection, leads to comparable levels or even to a sensible reduction in fuel consumption compared with the only-pilot or only-early inje...

Effects on combustion and emissions of early and pilot fuel injections in diesel engines

Study of the Influence of the Injection Parameters on Combustion Noise in a Common Rail Diesel Engine Using ANOVA and Neural Networks

The optimization method proposed in the present study consists of a multi-objective genetic algorithm combined with an experimental investigation carried out on a test bench, by using a DI Diesel engine. The genetic algorithm selects the injection parameters for each operating condition whereas the output measured by the experimental apparatus determines the fitness in the optimization process. The genetic algorithm creates a random population, which evolves combining the genetic code of the most capable individuals of the previous generation. Each individual of the population is represented by a set of parameters codified with a binary string. The evolution is performed using the operators of crossover, mutation and elitist reproduction. This genetic algorithm allows competitive fitness functions to be optimized with a single optimization process. For the determination of the overall fitness function the concept of Pareto optimality has been implemented. In this work, the input variables used for the optimization method are injection parameters like start of pilot and main injection, injection pressure and duration. The engine used is a FIAT 1929 cc DI diesel engine, in which the traditional injection system has been replaced by a common rail high pressure injection system.The competitive fitness functions were determined based on the measured values of fuel consumption, emissions levels (i.e. NOx, soot, CO, CO2, HC); combustion noise and overall engine noise, for each operating conditions. The optimization was performed for different engine speed and torque conditions typical of the EC driving cycles.

http://www.arturo.derisi.unisalento.it/Dowloads/Pubblicazioni/ASME_ICE_2002_2.pdf

Paolo Carlucci

Papers

Effects of Pilot Injection Parameters on Combustion for Common Rail Diesel Engines

Effects on combustion and emissions of early and pilot fuel injections in diesel engines

Study of the Influence of the Injection Parameters on Combustion Noise in a Common Rail Diesel Engine Using ANOVA and Neural Networks

A combined optimization method for common rail diesel engines

Preliminary Studies on the Effects of Injection Rate Modulation on the Combustion Noise of a Common Rail Diesel Engine